Apparatus for obtaining improved finishes on double reduced material



Oct. 11, 1966 Q w JAMES ETAL 3,277,686

APPARATUS FOR OBTAINING IMPROVED FINISHES ON DOUBLE REDUCED MATERIALOriginal Filed June 26, 1961 2 Sheets-Sheet l lNVE/V TORS Owen 14 Jamesfuyene Wafers o. w. JAMES ETAL 3,277,686 APPARATUS FOR OBTAININGIMPROVED FINISHES ON DOUBLE REDUCED MATERIAL 1961 Oct. 11, 1966 2Sheets-Sheet 2 Original Filed June 26,

' l/VVEA/TORS Owen M/. James fqqene R Wafers United States Patent 03,277,686 APPARATUS FOR OBTAINING IMPROVED FIN- ISI-IES 0N DOUBLEREDUCED MATERIAL Owen W. James and Eugene P. Waters, Baltimore, Md.,assignors, by mesne assignments, to Bethlehem Steel Corporation, acorporation of Delaware Original application June 26, 1961, Ser. No.124,889, now Patent No. 3,200,629, dated Aug. 17, 1965. Divided and thisapplication Dec. 18, 1964, Ser. No. 419,311 7 Claims. (Cl. 72-201) Thisis a division of application Serial No. 124,889, filed June 26, 1961,nowPatent No. 3,200,629.

The present invention relates to means for producing very thintin-coated ferrous sheet and strip material. More particulaly thepresent invention relates to novel apparatus for providing a superiorsurface finish upon very thin tin-coated ferrous sheet and stripmaterial.

Recently very thin tin-coated strip has been produced by rolling steelstrip in conventional fashion, coating the strip with tin according tonormal practice and then finally passing the coated strip through asecond cold rolling operation which reduces the strip and its coating toa still lighter gauge. Although the tin coating is softer than theferrous base, both the coating and the base metal are reducedapproximately proportionally. Reductions may be made to almost anyreasonable extent. However, the normal reduction is usually from 35 to50%. Thin coated strip material produced according to this method isknown as double reduced material since it has been passed through twoseries of reducing operations.

While double reduction produces excellent thin tin- ,coated stripmaterial possessing very satisfactory physical properties, trouble hasbeen experienced with the surface finish due to roll marks, staining andparticularly mottling of the surface.

Users of tin plate and strip, especially can manufacturers, are verydemanding with respect to the surface finish of the product andparticularly with respect to uniformity of finish. In addition, users oftin-coated products also desire various degrees of brightness of surfaceon the strip and sheet which they purchase.

Heretofore the mottled and uneven surface finishes on double reducedmaterial have been covered up by passing the double reduced materialthrough a skin pass rolling stand between rolls which have beenroughened by some expedient such as sand blasting. This operation breaksup the surface and results in a comparatively rough or coarse finishwhich more or less hides the underlying mottling. This solution of theproblem is not satisfactory, however, because the mottling is notcompletely hidden, many purchasers of tin coated product do not desire acoarse finish, and the roughened skin pass rolling operation adds anextra step to the double reduction operation.

The cold rolling of metal produces considerable heat as a result of thework done in reducing the metal. This heat must be removed to prevent aprogressive alteration in the size and shape of the roll pass due togradual expansion of the rolls as the heat builds up. Conventionalpractice is to flood the rolls with cooling water to remove the heat.

Cold reduction by rolling is usually conducted with a lubricating orrolling oil to prevent sticking of the metal to the roll surface and toreduce the horizontal friction factor so that reduction is more easilyaccomplished. Modern practice has almost universally been to form anemulsion of the lubricating oil and cooling water and apply the emulsionto the strip entering the roll bite. It has been thought that therolling oil and water emulsion acts as a unitary and homogeneous fluidmedium for both cooling and lubricating the rolling operation.

The present inventors have discovered that it is free water in the rollbite which causes the mottling of double reduced tin coated stripmaterial. In particular they have found that the conventional oil andwater emulsion tends to break down, especially when subjected to theheat and pressure of the roll bite. No practical method is known toprevent this breakdown as the stable emulsion point is very critical.The inventors have discovered, however, that if the reduction of thealready coated strip is carried out in a uniform lubricating oil mediumconsisting only of oil or of well mixed oil mediums which are thoroughlymiscible with each other the mottled surfaces are eliminated.Furthermore, they have discovered that if the rolling is carried outwith the correct lubricating regardless of changes in mlll speed, rolltemperatures and roll finishes, or surface conditions of materialentering the mill.

In order to cool the work rolls, the inventors apply cooling water tothe rear of the work rolls and provide means to prevent the coolingwater from reaching the entrance side of the work rolls where it couldenter the roll bite. These means include the use of special splashshields in combination with a novel matching of the work surfaces of thework rolls and the back-up rolls.

It is an object of the present invention to provide rolling millapparatus adapted to provide oil lubrication on the exit side of thework rolls and to prevent water from reaching the entrance side of thework rolls.

It is a still further object of the present invention to provide a workroll and back-up roll combination which Will prevent the migration ofwater films from the exit to the entrance side of the work rolls.

These and other objects and advantages will be recstruct-ures and inwhich:

FIGURE 1 shows in section an elevation of a rolling mill arrangedaccording to the present invention.

FIGURE 2 shows a section in plan of FIGURE 1 along line 22 with topback-up roll and top water shield flaps removed.

FIGURE 3 illustrates the conformation of the surface of the work rollsand the arrangement of the work rolls and the back-up rolls.

FIGURE 4 shows in expanded view the ends of the work rolls and theback-up rolls of the present invention.

FIGURE 5 is an isometric view of the entry water shield.

A section of a roll stand 12 is shown in outline in FIGURES 1 and 2.Back-up rolls 14 and 16 mounted in stand 12 are shown in section inFIGURE 1. rolls 18 and 20 are shown in section between back-up rolls 14and 16. Tin coated strip 22 is fed from a coil of '5 so as to eliminatea sharp edge along this side which might mar the bottom of strip 22 ifit should touch plate 42 At the rear of the bottom plate 42 of bothwater shields 36 and 38 are secured clamp members 46 having arm members47. As may be seen in FIGURES 1 and 2 entry water shields 36 and 38 maybe placed in position on both sides of strip 22 by sliding the shields36 and 38 across cross member 48 of roll stand 12 until the arm members47 of the clamps 46 engage the underside of member 48. Screw clamps, notshown, may be passed through arm members 47 from the bottom if desiredto engage cross member 48 to lock the two members 46 and 48 togethermore securely. During operation of the roll stand, shields 36 and 38, asshown in FIGURES l and 2, are positioned with their bottom plates underand very near but not touc 'ng the lower surface of the strip 22 passingto the bite of the work rolls while their side plates 40 are closelyadjacent the sides of the strip and their inclined top plates 44 arelocated over but spaced considerably away from the strip surface. Inorder to facilitate drainage of any splashed water from shield-s 36 and38, it is preferable that they be tipped rearwardly towards clamps 46 sothat moisture will not drip from bevel 43 onto the lower work roll. Fourwater shield flaps 50, 52, 54 not shown, and 56 are pivoted on shafts50a, 52a, 54a, not shown, and 56a supported by the mill stand structure12 as shown in FIGURES 1 and 2. Water shield flaps 50, 52, 54 and 56 arearranged somewhat outwardly of the sides 40 of water shields 36 and 38to more effectively shield the roll bite and the strip entering the rollbite from any splashed water. It will be noted that water shield flaps50, 52, 54 and 56 are iarcuately concave in two unequal sized arcstoward the mill rolls and are positioned adjacent the rolls in order toclose the spaces between the reducing and back-up rolls.

Positioned on the exit side of work rolls 18 and 20 are top water spraynozzles 58 and bottom water spray nozzles 60 which spray cooling wateron the exit sides of work rolls 18 and 20 respectively. Top water sprays58 are mounted upon a so-called water scoop 62 which comprises atrough-like structure extending along the rear of the work rolls havinga water wiper 64 mounted upon its lower section to bear against the worksurface of the work roll 18. Water wiper 64 may be com-posed of someflexible material and is designed to provide a water seal against thesurface of roll 18 so that substantially no water will pass from thearea on top of wiper 64 to the area adjacent the bottom. The coolingwater discharged against the surface of roll 18 by spray nozzles 58 runsdown the roll surface to wiper 64 which wipes the water from the surfaceand directs it into water scoop 62, which collects the considerablevolume of water and discharges it from the open ends of scoop 62 beyondthe edges of strip 22 where is can fall into a sump, not shown, underthe mill stand. Water scoop 62 and its associated water wiper 64 areactively pressed against the back of work roll 18 by the action of aircylinder 66. Air cylinder 66 also may be operated to retract scoop 62and wiper 64 out of the way when changing the rolls in stand 12. Bottomwater spray nozzles 60 discharge their cooling water against the rear ofbottom work roll 20 where both because of the effects of gravity andbecause work roll 20 is turning in the direction shown by the arrows inFIGURE 1, the water flows downwardly away from strip 22 and eventuallyinto the sump, not shown, under the mill. A water scoop such as 62 isthus unnecessary to prevent the spray from bottom cooling nozzles 60from contacting the strip 22.

A film of water from both groups of spray nozzles 58 and 60 is carriedon work rolls 18 and 20 respectively, on the surface thereof to theareas of contact between the said work rolls and their respectiveback-up rolls 14 and 16. Because of the very high pressure and closecontact between the work rolls and back-up rolls water cannot passbetween these rolls but is instead squeezed out and forced along therolls to the sides thereof where it drains away. It is important thatthe surfaces of the back-up and work rolls be smooth and free from anyimperfections or scuff marks which might allow water to pass between therolls.

There is considerable agitation and violent splashing of water to therear of the rolls but splash water shields 36 and 38 and water shieldflaps 50, 52, 54 and 56 effectively shield strip 22 near the entranceside of rolls 18 and 20, and also shield the work surface of theentrance side of the work rolls 18 and 20 themselves from any waterwhich may be splashed or thrown from the exit side of the mill. Watershields 36 and 38 are mounted on clamps and water shield flaps 50, 52,54 and 56 are pivotally mounted so that they can be removed or swungclear during the periodic changing of the rolls.

While the back-up rolls 14 and 14 effectively squeeze the cooling waterfrom the surface of the rotating work rolls and the various watershields described above effectively prevent any water droplets fromsplashing from the area contacted by the cooling water to the enteringstrip or the roll bite of the mill, it has been found that water maystill work its way around from the exit side of the work rolls to thework surface on the entrance side of the work rolls. The inventorsprevent this by beveling the ends of the back-up rolls and by cuttingshoulders on the ends of the Work rolls directly opposite the inner endsof the bevels on the back-up rolls. This structural relationship isshown in FIGURES 3 and 4 where the work surfaces 68 and 70 of work rolls18 and 20 respectively have been cut back at 72 providing a sharpshoulder at 74 exactly opposite the edge 76 of the bevel surface 78 onback-up rolls 14 and 16. Work rolls 18 and 20 are beveled at 80. Cut 72may initially be formed about one-eighth of an inch deep so that as therolls are subsequently reground the cut will remain at least onethirty-second of an inch deep. One thirty-sec- 0nd of an inch isapproximately the minimum desirable. However the cut may be made deeperthan one-eighth inch initially if desired. It may be clearly seen inFIG- URE 4 that the cut back surface 72 of work roll 18 is opposite. thebeveled surface 78 of back-up roll 14 with the edge 76 of bevel surface78 of back-up rolls 14 exactly in line with and meeting the edge ofshoulder 74 between the work surface 68 and the cut back surface 72 ofwork roll 18. The exact dimensions of the bevels on both the back-up andthe work rolls and the cut back portions on the work rolls are notcritical. It will be understood, however, that shoulder 74 is preferablysubstantially a sharp shoulder and the edge of this shoulder and thebevel edge 76 must be substantially exactly in line with each other. 7

While the foregoing is the inventors preferred embodiment and isparticularly effective other configurations of rolls can be used, themost important consideration being that the working surfaces of the workrolls and back-up rolls be maintained of equal length and in exactalignment with each other.

It is particularly important in the cold rolling of coated materials toprovide the correct rolling lubricant.

It has been found that excellent even textured so-called matte surfacesor dull surface finishes can be obtained by using a glyceride of a fattyacid as the lubricant on the entry side of the mill. By fatty acid itshould be understood that the substances referred to are the fatty acidshaving suitable rolling lubrication properties, i.e., in general thosefatty acids containing from 6 to 22 carbons. For example, pure palm oilor other comparable vegetable oil such as cottonseed oil or soybean oilconstitute satisfactory lubricants. Other suitable fatty oils such asoils of animal or vegetable origin may also be used. If a brighter butalso even textured surface finish is desired alkyl esters of fatty acidsmay be mixed with these rolling oils in various proportions dependingupon how bright a surface is desired. Alkyl esters of fatty acids arecompletely miscible with these rolling oils so that a homogeneouslubricant is obtained. Any suitable commercial chemical proportioningequipment may be used to correctly mix and proportion the rolling oiland alkyl esters.

As an example of our invention, we start with a coil of tinplateproduced in the usual manner on an electrolytic tinning line. The tincoating on the tinplate is heavier than that desired in the finalproduct, in order to allow for reduction of the tin coating in the finalrolling operation.

The coil is placed on feed reel 24, and the end of the strip is threadedthrough work rolls 18 and 20, past rolls 28 and 29, and secured totakeup or tension reel 30. As the rolling operation is started, oile.g.,palm oil, is sprayed onto the upper and lower sides of strip 22 by meansof sprays 32 and 34 prior to its entry into the roll bite. On the rearor exit side of the rolls, cooling Water is sprayed onto the work rollsby means of water sprays 58 and 60. The work rolls and the tension onthe strip are adjusted to effect a reduction of the strip gauge of 40%.The resultant product is a thin tin plated strip having a moderatelydull but uniform textured surface, suitable for the majority of uses towhich thin tin plate can be put.

In producing strip on which a much brighter surface was desired, wefollowed the same procedure as given above except that instead of usingpalm oil alone as the lubricant we used a mixture of 80% palm oil and20% alkyl esters of fatty acids.

It will be recognized that the present invention provides a verypractical and reliable method and means for obtaining even textureddouble reduced strip material in a single cold rolling stand without theuse of any expensive or complicated special equipment.

Although the present invention has been described here in inconsiderable detail, it should not be limited narrowly to the exact andspecific particulars disclosed and/or described but may also includesuch substitutes, modifications or equivalents as are included withinthe scope and spirit of the invention or pointed out in the appendedclaims.

We claim:

1. A rolling mill stand for cold rolling of tin coated steel strip, saidrolling mill stand having two back-up rolls provided with centralworking surfaces and beveled ends, two work rolls having central workingsurfaces of the same width as those of the back-up rolls terminating insharp corners and cut back portions in line with and contacting theinner edges of the bevels on the back-up rolls, oil sprays on the entryside of the work rolls to spray water-free lubricating oil on the stripentering the roll bite, water sprays on the exit side of the Work rollsto spray cooling water on the rear of the reducing rolls, a troughhaving a wiper blade in contact with the upper work roll below the watersprays for said roll to prevent cooling water from running into the rollbite on the exit side and water shields on the entry side of the millclosely adjacent to the work rolls and back-up rolls to prevent waterfrom splashing from the exit side to the entrance side of the mill.

2. Apparatus for cold rolling metallic strip comprising work rollshaving work surfaces terminating in sharp cornered shoulders, back-uprolls having Work surfaces terminating in beveled ends, the shoulders onthe Work rolls being in alignment with the inner edges of the beveledend portions of the back-up rolls, upper and lower water spray meansdirected at the exit side of the work rolls, a water wiper and anassociated trough located adjacent the exit side of the upper work roll,with the wiper in contact with said roll to remove and trans port waterfrom the rear surface of said upper work roll, and means to preventsplashing of Water from the exit side to the entrance side of the rollsand on to the mate rial entering the roll bite comprising two splashshields, mounted adjacent the sides of the strip, having portionsextending partly over and partly under each side of the strip adjacentthe roll bite,-and four splash shields mounted outboard of the two firstmentioned shields, each of said four shields mounted adjacent to andextending into the bite between the work rollsand adjacent back-up rollsand having arcuate edges conforming with the contours of said rolls.

3. Apparatus for cold rolling metallic strip comprising:

(a) work rolls having work surfaces terminating in sharp corneredshoulders,

(b) back-up rolls having work surfaces terminating in bevelled ends, theshoulders on the work rolls being in alignment with the inner edges ofthe bevelled end portions of the back-up rolls,

(c) water spray means directed at least at the exit side of the upperwork roll,

(d) a water wiper and an associated trough located adjacent the exitside of the upper work roll with the wiper in contact with said roll toremove and transport water from the rear surface of said upper Workroll, and

(e) means to prevent splashing of water from the exit side to theentrance side of the rolls and onto the material entering the roll bitecomprising splash shield means substantially vertically disposed,adjacent the edges of the entering strip, and extending into the bitebetween the Work rolls and adjacent back-up rolls.

4. A four-high cold rolling mill comprising:

(a) a pair of back-up rolls having bevelled ends,

(b) a pair of Work rolls having sharp cornered shoulders aligned withthe inner ends of the bevels on said back-up rolls and having portionsof reduced diameter outboard of said shoulders,

(c) spray means for applying water free lubricating oil to the entrancearea of the work rolls,

(d) spray means for applying cooling water to the exit side of the workrolls, and

(e) splash shield means to prevent any cooling water from splashing fromthe exit side of the work rolls to the entrance area of the Work rolls.

5. Apparatus for cold rolling metallic strip comprising:

(a) work rolls having work surfaces terminating in sharp corneredshoulders at least of an inch deep,

(b) back-up rolls having work surfaces terminating in bevelled ends,

(0) the shoulders on the work rolls being in alignment with the inneredges of the bevelled end portions of the back-up rolls,

(d) means for applying lubricating oil tothe entrance area of the workrolls,

(e) means for applying cooling water to the exit side of the work rolls,

(f) splash shield means to prevent cooling water from splashing from theexit side of the Work rolls to the entrance area of the Work rolls.

6. Apparatus for cold rolling metallic strip comprising:

(a) work rolls having work surfaces terminating in sharp corneredshoulders,

(b) back-up rolls having work surfaces terminating in recessed ends,

(c) the work surfaces on work rolls being in exact alignment with thecontact surfaces of the back-up rolls,

(d) means for applying lubricating oil to the entrance area of the workrolls,

(e) means for applying cooling water to the exit side of the work rolls,and

(f) means to prevent cooling water from splashing from the exit side ofthe work rolls to the entrance area of the work rolls.

7. Apparatus for cold rolling metallic strip comprising:

(a) work rolls having work surfaces terminating in sharp corneredshoulders,

(b) back-up rolls having surfaces terminating in bevelled ends,

(c) the work surfaces on the work rolls being in exact alignment andcoextensive with the contact surfaces of the back-up rolls,

(d) spray means for applying lubricating oil to the entrance area of thework rolls,

(e) spray means for applying cooling water to the exit side of the workrolls,

(f) first splash shield means mounted on either side of and partly overand under the strip adjacent the roll bite, and

(g) second splash shield means mounted outboard of and above and belowthe first shield means with extensions extending partially into the rollbite.

References Cited by the Examiner UNITED STATES PATENTS 161,786 4/1875Harris et a1 72--201 1,963,539 6/ 1934 Zuber 72201 1,978,895 10/1934Clark 72201 1,988,679 1/1935 Badlam 72201 2,017,403 10/1935 Lorig et al.7245 2,344,996 3/1944 McConnell 72243 CHARLES W. LANHAM, PrimaryExaminer. H. D. HOINKES, Assistant Examiner.

1. A ROLLING MILL STAND FOR COLD ROLLING OF TIN COATED STEEL STRIP, SAIDROLLING MILL STAND HAVING TWO BACK-UP ROLLS PROVIDED WITH CENTRALWORKING SURFACES AND BEVELED ENDS, TWO WORK ROLLS HAVING CENTRAL WORKINGSURFACES OF THE SAME WIDTH AS THOSE OF THE BACK-UP ROLLS TERMINATING INSHARP CORNERS AND CUT BACK PORTIONS IN LINE WITH AND CONTACTING THEINNER EDGES OF THE BEVELS ON THE BACK-UP ROLLS, OIL SPRAYS ON THE ENTRYSIDE OF THE WORK ROLLS TO SPRAY WATER-FREE LUBRICATING OIL ON THE STRIPENTERING THE ROLL BITE, WATER SPRAYS ON THE EXIT SIDE OF THE WORK ROLLSTO SPRAY COOLING WATER ON THE REAR OF THE REDUCING ROLLS, A TROUGHHAVING A WIPER BLADE IN CONTACT WITH THE UPPER WORK ROLL BELOW THE WATERSPRAYS FOR SAID ROLL TO PREVENT COOLING WATER FROM RUNNING INTO THE ROLLBITE ON THE EXIT SIDE AND WATE SHIELDS ON THE ENTRY SIDE OF THE MILLCLOSELY ADJACENT TO THE WORK ROLLS AND BACK-UP ROLLS TO PREVENT WATERFROM SPLASHING FROM THE EXIT SIDE TO THE ENTRANCE SIDE OF THE MILL.